Manganese is a transition metal with multiple valencies (1, 2, 3, 4, 6 and 7), widely distributed throughout
the earth’s crust and present in most plant and animal tissue. As a metal, it is similar to iron and is used
industrially in the manufacture of steel, batteries and ceramics. Manganese toxicity among workers in these
industries, and in manganese ore miners, is well documented. In addition to its potential for toxicity,
manganese is also an essential nutrient. In the human body, it is stored in tissues rich in mitochondria (e.g.
the liver and pancreas) and is required for the metabolism of amino acids, proteins, and lipids. Manganese
salts have also been used therapeutically, for example in the treatment of psoriasis.